login
Numbers that are the product of two distinct primes and they are sum of two consecutive products of two distinct primes.
1

%I #2 Mar 31 2012 12:38:27

%S 69,77,85,106,115,134,143,159,178,187,201,217,226,237,262,267,291,301,

%T 327,355,381,395,403,411,415,422,427,437,447,502,527,565,586,597,614,

%U 623,633,649,669,674,687,713,758,763,789,793,818,849,893,898,951,959

%N Numbers that are the product of two distinct primes and they are sum of two consecutive products of two distinct primes.

%e 6,10,14,15,21,22,26,33,34,35,38,39,46,..A006881 Numbers that are the product of two distinct primes 69=34+35, 77=38+39, 85=39+46,.. 69=3*13, 77=7*11, 85=5*13,..

%t f[n_]:=Last/@FactorInteger[n]=={1,1}; a=6;lst={};Do[If[f[n],p=a+n;If[f[p],AppendTo[lst,p]];a=n],{n,9,7!}];lst

%Y Cf. A006881, A168474

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Nov 26 2009